Reciprocating electric hammer



A. BETTICA RECIPROCATING ELECTRIC HAMMER Aug. 20, 1929.

Filed July 6, 1926 14 1s zoe 2 7 1 aan Patented A ug. l20, 1929.

UNITED ASTATES .e 1 1,725,504 PATENT oFFicE.

RECIPROCATING ELECTRIC HAMMER.

Application lled July 6,

This invention relates to reciprocating electric hammers of the kind comprising a magnetlc metal cased solenoid, whose inner core is moved to and fro by the actions of material for the coil of the 'solenoid is constituted b substantially C-shaped plates or strips, ri bed in order to strengthen the strips and reduce their bulkincss, and placed radially round the coil, which arrangement ensures the conveyance of electromagnetic forces, eliminates eddy or Foucault currents, provides for effecting coolin-g of the inner parts owing to the large surface of the armor exposed to the air and constitutes a protection for the inner coil and is a part of the outer casing of the hammer.

Theinvention also consists of the novel construction of the inner core, or4 cores, which is made of a bundle of ribbed strips of magnetic metal, radially disposed and so groovedand compressed into each other that the whole bundle is kept together without the aid of rivets.

A form of the invention, as ap lied to a percussive hammer, is illustrated, y way of example, on .the accompanying drawing, whereonz- Figure 1 represents a longitudinal section -through the machine.

Figure 2 represents a cross section on line Figure 3,represents a cross section on line 3-3 of Fig. 1.

' rent.

Referring to the'drawings; the tool has a coil 1 arranged in a cage 2 of C-shaped ribbed plates 3 of magnetic material placed around the coil. The plates 'extend parallel to the 1926. Serial N'o. 120,753.

axis of the coil 1 and are radial thereto. The coil carries inside a vcore 4, made of magnetic metal plates, radially disposed, and tightly grooved into each other, the outer percussive end 5 being soldered. Another core G, which does not move, is placed inside the coil, and is hollow in order to contain a' helical spring 7. This core is made similar to core 4 and its left hand ends are soldered to form a head. The helical'spring 7 tends to, force the core 4 out of the coil 1.4 Another spring 9 acts in theo: opposite direction, after the core has imparted a blow on the tool stem 8 of the tool 25. l

A regulator 10 having a set screw 11 is placed at one end of the spring 7, so that by turning the regulator 10, the reaction of the spring can be adjusted. The back casing 12 of the hammer has apivot 13 on one side and a movable nutlatch 14 on the other side, al- 'lowing the back cover 15 and handle 16 to swing round and leave open the interior of .the machine for inspection, oiling or cleanmg.

The handle 16 has a lever 17 pivoted in it, which acts on a rod 18, by means of a spring 19, operating a switch 20 placed inside the casing 12. This casing 12 also bears a ring 21 holding a double line conduct-ing cable 22 to be connected to a suitable source of electric energy. A front casing 23 keeps together the C-shaped plates 3 by means of a split ring 27 0f two semi-circular parts and screws 27 and carries the tool 25 by means of a hard metal collar The second core is not always necessary; in hammers of a short. tool) stroke said core can be eliminated, as illustrated in Fig. 5, where the hammer is provided only with the movable axe shaped core 4, formed by a bundle 'of stripsyradially disposed'like -the i A1 o:f\Fig. 1, and the outer casin 2a also formed by radial strips is suitably en arged in correspondence with the enlarged coil diameter.

All the other parts are identical to the corresponding arts of Fig. 1. v

Fig. 6 s ows the electric connection of the hammer l is the coil attached to the feeder 30 by a hve current plug 31 and in the circuit whereof is inserted a ulsating switch 20"; 4b

illustrates the movab e core; 25bthe tool and 7 b the opposing spring.

To operate theV hammer the cable conductor is connected to an ordinary live current plug 31. Then whilst grasping the handle of the hammer the operator depresses the rod thereby closing the switch sectors and completing the circuit of the current in the coil, whose core is normally constrained by the spring against the stem of the tool. Immediately the coil 1 is energized and the core is drawn inside thus compressing the spring. But during the passage of the current between a positive alternation or phase and the next negative alternation or phase the spring acts upon the core causing it to withdraw violently to its original posit-ion thus imparting a blow to the stem of the percussive tool.

Therefore the hammer gives as many strokes per minute as the number of alternations or phase given by the electric current, that is `to say twice the number of cycles. For instance, with an alternating current of 60 cycles the hammer strikes 19.0l blows per second. By speciall adjusting the elastic reaction of the bac spring, or by adjusting also the reaction of the front shock absorbing spring, it is possible to reduce the strokes to the half or to the quarter,that is to say to an exactly submultiple number.

What I claim is: v

l. In an4 electromagnetic hammer, a striker comprising radial longitudinally directed plates soldered together at their impact end, a core, spring means tosupport the core for free oscillations, a device .to adjust the tension of the spring means a winding surrounding the core and in which the core moves, a laminated magnetic field mem- .ber whose laminations extend longitudinally of the core and winding, casing members connect-ing the ends of the laminations and supporting said spring means, 'a tool holding means on one casing member and a handle on the other casing member, said core reciprocating substantially in phase with the current.

2. In an electromagnetic hammer, the combination with a casing member; of a closure Y member hinged thereto and when swung on said hinge exposing the entire end of said casing member, a handle forming part of the closure member, electric contact operating means in the closure member, a pair of electric contacts inthe casing member arranged for actuation by said operating means, and a grip on the handle for actuating said operating means.

3. In an electromagnetic hammer, a held winding, a magnetic member enclosing the winding, and a central core divided into two portions, each composed of longitudinally directed radial plates, the plates of each portion connectedtogether at one end by a fused metal connection, one of said portions being stationary and the other reciprocable, a spring for each end of the latter portion, means for adjusting spring tension and means for supplying alternating current to said winding, said reciprocable portion oscillating with the current supplied.

4. In an electro-magnetic hammer, the combinat-ion with a fixed counter-core; of a movable core acting as striker, spring means supporting the movable core for free oscillation, an energizing coil for the core, means for supplying at will and continuously alternating current to said coil, the core making a reciprocation for each current phase, a magnetic eld Imember surrounding the counter-core,

core and coil, and constituted by radial longitudinally directed ribbed plates and cover members'secured on the opposite ends of said plates, said plates and cover members forming a casing orthe hammer and acting at the same time as magnetic circuit, body and support of the hammer and heat radiating mem- 5, In an. electro-magnetic hammer, the combination of a movable core constituted by radial plates tightly grooved into each other, a percussion member on one end of the core, springs at the opposite ends of said movable core to support the core for free oscillation, means to regulate the tension of one of said springs, an energizing coil for the core, a

hand operated switch vto feed alternating i current to said c oil at will and continuously,`

support of the hammer and heat radiating member.l l y In testimony that I claim the foregoing as my invention, I have signed my. name.

ALBERTO BEATTICA. 

